| Themes > Science > Physics > Electromagnetism > Magnetostatics > Magnetic Field > Magnetic fields and how to make them > Working in three dimensions |
With the force, velocity, and field all perpendicular to each other, we have to work in three dimensions. It can be hard to draw in 3-D on a 2-D surface such as a piece of paper or a chalk board, so to represent something pointing in the third dimension, perpendicular to the page or board, we usually draw the direction as either a circle with a dot in the middle or a circle with an X in the middle. Think of an arrow with a tip at one end and feathers at the other. If you look at an arrow coming toward you, you see the tip; if you look at an arrow going away from you, you see the X of the feathers. A circle with a dot, then, represents something coming out of the page or board at you; a circle with an X represents something going into the page or board. The following diagram shows the path followed by two charges, one positive and one negative, in a magnetic field that points into the page: |
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Information provided by: http://physics.bu.edu |